This invention relates generally to trocar systems including obturators and, more specifically, to optical obturators including an integral tip and shaft.
Trocar systems have been of particular advantage in facilitating less invasive surgery across a body wall and within a body cavity. This is particularly true in abdominal surgery where trocars have provided a working channel across the abdominal wall to facilitate the use of instruments within the abdominal cavity.
The trocar systems of the past typically included a cannula, which provides the working channel, and an obturator that is used to place the cannula across the abdominal wall. The obturator is inserted into the working channel of the cannula and pushed through the abdominal wall with a penetration force of sufficient magnitude to result in the penetration of the abdominal wall. Once the cannula is in place, the obturator can be removed.
Some prior art obturators have included a transparent plastic tip that is bonded onto the end of a shaft that is typically metallic, such as a stainless steel shaft. The cost of producing a stainless steel shaft is typically very high due to the cost of fabrication and the raw material cost. Additional cost is incurred to produce the plastic tip and to attach the plastic tip to the shaft. The plastic tips are usually produced through an injection molding process and the tips are typically bonded to the shaft. Other prior art obturators include the metallic shaft with the transparent plastic tip overmolded onto the shaft.
The transparent plastic tip provides the obturator with visualization properties. The optical obturators are configured to enable the insertion of an optical instrument that facilitates visualization of tissue during the insertion of the obturator through a body wall. During use, the optical obturator is typically inserted into a trocar seal and cannula. A conventional laparoscope is then inserted into the proximal end of the optical obturator and advanced to the distal tip of the obturator. An endoscopic video camera may be attached to the proximal end of the laparoscope and the surgeon may axially advance the trocar system through the body wall. As the surgeon advances the trocar through the body wall, the surgeon can visually observe the tissue as it is being traversed via a video monitor that is connected to the endoscopic video camera. The laparoscope facilitates the determination of when the body wall has been completely traversed by the trocar. Once the trocar has traversed the body wall, the obturator and laparoscope may be removed, leaving the trocar seal and cannula disposed across the body wall to provide an access channel into the body cavity for the insertion of laparoscopic instruments.
Other prior art optical obturators are fabricated as a single-piece, including a shaft and an integral tip, and are molded from a transparent material, such as a polymeric material. For instance, some prior art single-piece optical obturators are injection molded. The transparent material of which the optical obturator is formed facilitates visualization of tissue during the insertion of the obturator through a body wall. The shaft portion of the optical obturator extends along an axis between a proximal end and a distal end with a lumen therebetween. The lumen of the shaft is sized and configured to receive a conventional optical instrument, such as a laparoscope For practicality purposes, the outer surface of an optical obturator must be designed to fit within a standard, conventional cannula. The wall thickness of the optical obturator is, therefore, typically determined by the standard sizes of the trocar cannulas and the laparoscopes that have gained acceptance in the surgical environment. For example, one standard size trocar cannula has an inside diameter of 11.5 mm and the optical obturator must be designed to fit within this standard cannula. By way of example, the optical obturator must also be designed to accommodate the insertion of a standard laparoscope, such as a 10 mm laparoscope, into the shaft of the optical obturator to enable the visualization of tissue fibers through the tip of the obturator. Continuing with the example, the outside diameter of the optical obturator may be about 11.4 mm while the inside diameter of the optical obturator may be about 10.1 mm. The diameters in this example result in a very thin wall thickness of about 0.65 mm, and the length of the optical obturator typically ranges from about 205 mm to about 255 mm. Other, smaller, optical obturators may include a length ranging from about 120 mm to about 205 mm and have an outside diameter of about 6.9 mm and an inside diameter of about 5.6 mm, again resulting in a wall thickness of about 0.65 mm. These smaller obturators accommodate 5.5 mm laparoscopes, a common size, and fit into cannulas having an inner diameter of about 7.0 mm. The properties of the materials of which the prior art single-piece optical obturators are fabricated make it difficult to mold a complete part with a thin wall over such a long length; so the shaft portion of the prior art single-piece optical obturators include a relatively thick wall of about 1.18 mm or larger.
Having a thicker wall throughout the length of the shaft increases the overall outside diameter of the trocar assembly. The use of a trocar assembly having a larger overall outside diameter along its length may lead to increased trauma to a patient during use Accordingly, there is a need in the art for a process of fabricating a single-piece optical obturator having a thinner wall than prior art single-piece optical obturators and that can be manufactured at a lower cost in comparison to the prior art multiple-piece optical obturators.